Known process for overmolding silicone onto a plastic component involves using an upper mold plate and a lower mold plate forming a cavity therebetween. The plastic component is placed into the cavity and then the upper and lower mold plates are closed and liquid silicone is injected into the mold and cured about the plastic component to form a finished component. The upper and lower mold plates are then separated and the finished component is removed from the removed from the cavity. The problem with this technique is that during the injection of the silicone material an interference fit between the plastic component and the mold cavity is required. The upper and lower mold plates are machined to very tight tolerances. However, it is difficult to maintain the same tight tolerances for the plastic component.
If the plastic component is undersized, this will cause the mold cavity to have an excessive clearance. Since silicone has such a low viscosity, a thin layer of silicone will squirt out between the cavity and the component creating unwanted excess material in what is commonly called “flashing”. This flashing must then be removed from the component during an additional reworking process which not only increases manufacturing labor and time, but may also cause damage to the component or the silicone seal. On the other hand, if the plastic component is oversized, this will cause loading the component into the cavity to be difficult and create a misalignment that could lead to damage of the mold and/or the component, This the finished component will not be usable and will need to be scrapped.
Alternatively, the plastic component could be machined to a tight enough tolerance to eliminate over or undersized components. However, the machining operation would undesirable increase manufacturing costs and time of the plastic component.
An improved method of forming a silicone seal around a plastic component that compensates for dimensional variations in the component remains desired.
The subject matter discussed in the background section should not be assumed to be prior art merely as a result of its mention in the background section. Similarly, a problem mentioned in the background section or associated with the subject matter of the background section should not be assumed to have been previously recognized in the prior art. The subject matter in the background section merely represents different approaches, which in and of themselves may also be inventions.